Most expectant women know they might suffer from morning sickness and swollen ankles during pregnancy, but other physical problems, such as constipation, might be left out of the discussion at the doctor's office. Pregnant women often suffer from both increased urination and decreased excretion.

Onset of Constipation

Constipation is caused in part by the increase in progesterone that happens throughout pregnancy. Progesterone causes the digestive tract muscles to relax so food moves more slowly through the intestines, which allows your body to absorb more nutrients from the food. The most dramatic rise in progesterone levels happens between the ninth and 32nd weeks of pregnancy, which means constipation is most likely to start any time during this these weeks. Another cause of constipation is the increased size of the uterus, which puts pressure on the bowels. As your uterus grows larger, so does the chance you will suffer from constipation, but constipation caused by pressure on the bowels doesn't usually occur until the later stages of pregnancy.

Constipation Symptoms

People who are constipated usually have some difficulty using the bathroom. They may also have more infrequent and painful bowel movements or may not be able to void completely during a bowel movement. Although bowel habits vary from person to person, going without a bowel movement for more than three days is too long, according to a WebMD article titled "The Basics of Constipation." Expectant women who suffer from constipation should see a doctor if her bowel movements are more than three days apart.

Moving Things Along

Pregnant women can help the digestive process along by eating foods high in fiber and by drinking plenty of water. In fact, constipated or not, pregnant women should drink eight 8-ounce glasses of water each day, according to a What to Expect article titled "Drinking Enough Water During Pregnancy." Daily exercise also helps. Be sure to clear any exercise program ahead of time with your doctor, however. In addition, try not to hold any urges -- take care of them as soon as possible after you feel them. Prenatal vitamins that contain large amounts of iron can contribute to constipation, so talk to your doctor about switching to a lower-dose version.

Warning Signs

Constipation can lead to other health issues. Straining to pass a bowel movement can cause hemorrhoids, which are painful, swollen veins around the rectum. In most cases, hemorrhoids will go away once the baby is born, but, if they are bleeding or causing you severe pain, see your doctor for treatment. Constipation can also indicate a more serious problem if other symptoms, such as abdominal pain or the passing of blood, accompany it. If this happens, see a doctor as soon as possible.